HP P9000 Provisioning for Mainframe Systems User Guide (AV400-96369, October 2011)

Thin provisioning
Thin provisioning is an approach to managing storage that maximizes physical storage capacity.
Instead of reserving a fixed amount of storage, it simply removes capacity from the available pool
when data is actually written to disk.
Thin Provisioning Z
Though basic or traditional provisioning strategies can be appropriate and useful in specific
scenarios, they can be expensive to set up, awkward and time consuming to configure, difficult to
monitor, and error prone when maintaining storage.
Thin Provisioning Z is a simpler alternative to the traditional provisioning methods. It uses thin
provisioning technology that allows you to allocate virtual storage capacity based on anticipated
future capacity needs, using virtual volumes instead of physical disks.
Overall storage use rates may improve because you can potentially provide more virtual capacity
to applications while fully using fewer physical disks. It provides lower initial cost, greater efficiency,
and storage management freedom for storage administrators. In this way, Thin Provisioning Z
software:
• Simplifies storage management
• Self-balances resource use and optimizes performance
• Maximizes physical disk usage
Thin Provisioning Z concepts
Thin Provisioning Z is a volume management feature that allows storage managers and System
Administrators to efficiently plan and allocate storage to users or applications. It provides a platform
for the array to dynamically manage data without host involvement.
Thin Provisioning Z provides two important capabilities: thin provisioning of storage and enhanced
volume performance.
Thin Provisioning Z is more efficient than traditional provisioning strategies. It is implemented by
creating one or more Thin Provisioning Z pools (THP pools) of physical storage space using multiple
LDEVs. Then, you can establish virtual THP volumes (THP V-VOLs) and connect them to the individual
THP pools. In this way, capacity to support data can be randomly assigned on demand.
THP V-VOLs are of a user-specified logical size without any corresponding physical space. Actual
physical space (in 38-MB pool page units) is automatically assigned to a THP V-VOL from the
connected THP pool as that volume’s logical space is written to over time. A new volume does not
have any pool pages assigned to it. The pages are loaned out from its connected pool to that THP
volume until the volume is reformatted or deleted. At that point, all of that volume’s assigned pages
are returned to the pool’s free page list. This handling of logical and physical capacity is called
thin provisioning. In many cases, logical capacity will exceed physical capacity.
Thin Provisioning Z enhances volume performance. This is an automatic result of how THP V-VOLs
map capacity from individual THP pools. A pool is created using from one to 1024 LDEVs (pool
volumes) of physical space. Each pool volume is sectioned into 38-MB pages. Each page is
consecutively laid down on a number of RAID stripes from one pool volume. The pool’s 38-MB
pool pages are assigned on demand to any of the THP V-VOLs that are connected to that pool.
Other pages assigned over time to that THP V-VOL randomly originate from the next free page
from other pool volumes in that pool.
Setting up a Thin Provisioning Z environment requires a few extra steps. You still configure various
array groups to a desired RAID level, and then create one or more volumes (LDEVs) on each of
them (see (page 33)). But then you set up a Thin Provisioning Z environment by creating one or
more THP pools of physical storage space that are each a collection of some of these internal
LDEVs (THP pool volumes). This pool structure supports creation of Thin Provisioning Z virtual
volumes (THP V-VOLs), where 38-MB pages of data are randomly assigned on demand.
10 Introduction to provisioning